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81.
JOSEF PFEILSCHIFTER WOLFGANG EBERHARDT RICHARD HUMMEL DIETER KUNZ HEIKO MÜHL DOROTHEA NITSCH CHRISTOPH PLÜSS GABY WALKER 《Cell biology international》1996,20(1):51-58
In recent years, NO, a gas previously considered a potentially toxic chemical, has become established as a diffusible universal messenger mediating cell—cell communication throughout the body. In mammals, NO is a recognized mediator of blood vessel relaxation that helps to maintain blood pressure. In the central nervous system NO acts as a non-conventional neurotransmitter and participates in the establishment of long-term plasticity required for memory formation. In addition, NO is responsible for some parts of the host response to sepsis and inflammation and contributes to certain disease states. A number of strategies have emerged with regard to a pharmacological control of pathological NO overproductions. This review will discuss these novel therapeutic approaches that may provide new means for clinical medicine. 相似文献
82.
Macrophage Functional Heterogeneity in the <Emphasis Type="Italic">in vitro</Emphasis> Induced Immune Response 总被引:1,自引:0,他引:1
WILLIAM S. WALKER 《Nature: New biology》1971,229(7):211-212
RNA from antigenically stimulated peritoneal macrophages is immunogenic in vitro1–4. The studies of Fishman and Adler5–6 suggest that the peritoneal macrophage population consists of at least three functionally distinct subpopulations. Although most peritoneal macrophages act as scavenger cells7, a second population—possibly less than one cell per 1,000—consists of cells that produce but do not necessarily secrete antibody8,9 and respond to antigen by synthesizing informational RNA. On transfer to normal lymphoid cells, this RNA elicits IgM antibody with the allotypic specificity of the macrophage donor10. A third type of macrophage gives rise to the RNA-antigen complex responsible for the in vitro synthesis of IgG antibody with the allotypic specificity of the lymphocyte donor10. 相似文献
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MURRAY SHEILAH; WOODBINE MALCOLM; WALKER THOMAS KENNEDY 《Journal of experimental botany》1953,4(2):251-256
1. Forty-three strains of moulds, selected from ten species,were examined to ascertain their capabilities as producers offat, when grown in four different solutions of nutrient inorganicsalts together with sucrose. The three highest yields of feltwere given by Penicillium javanicum van Beyma, P. Soppi Zaleski,and Aspergillus nidulans Eidam, in that order. The fat contenton felt weight was maximal at 34·8 per cent, with P.Soppi, at 28·4 per cent. with Fusarium lini(1), and at25·8 per cent. with A. nidulans; on sugar utilized itwas maximal at 11·4 per cent. with P. Soppi, at 7·9per cent, with A. nidulans, and at 5·6 per cent. withF. lini(1). 2. Other moulds considered worthy of further trial were P. spinulosum,P. aurantiobrunneum, F. graminearum, A. flavus, F. oxysporum,A. clavatus, and P. oxalicum. 相似文献
85.
When lettuce pith explants were cultured for 14 d on a xylogenicmedium, tracheary elements differentiated in greatest numbersbetween 25 and 30 °C. Numbers were depressed at lower temperaturesby slower development and at higher temperatures by adverseprocesses. The data did not support previous suggestions ofa great stimulation of xylogenesis above 30 °C and of aspecial sensitivity to low temperatures. Tracheary elements differentiated in various spatial patterns:as clumps in the peripheral callus, as strands which extendedradially and longitudinally from some of these clumps, as individuallarge tracheids especially at the more extreme temperatures,and as short strands associated with nodules and roots thatformed at favourable temperatures. We suggest that indoleacetic acid (IAA) has various roles inthe positional control of these tracheary patterns: (1) IAAdestruction at the explant surface leads to concentration gradientsthat inhibit tracheary induction close to the surface; (2) IAAtransport from the source in the culture medium to sinks especiallyat the explant surface, coupled with autocatalytic flow facilitation,leads to canalization along pathways that become meristematicand then trachcary strands; (3) the IAA flux (and associatedproton flux) along these pathways tend to orient cortical microtubulesat right angles to the flow, by some mechanism as yet unknown,and hence to control the orientation of tracheary element elongationand secondary wall banding. These suggestions, supported bymorphometric studies of tracheary element dimensions and orientations,and by experiments with localized IAA application, lead to ageneral interpretation of the development of polarity in plants. IAA, Lactuca sativa, lettuce, pith explants, positional control, temperature effects, tracheary element differentiation 相似文献
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Cultures of Macrocystis integrifolia zoospores have been madein sea-water enriched with phosphate and nitrate. It has beenshown that the spores and gametophytes possess nuclei with thehaploid complement of 16 chromosomes while the sporophyte nucleiare diploid with 32 chromosomes. Spores were transported byair from British Columbia to the British Isles. Results arecompared with other Laminariaceae. 相似文献
88.
STUDIES IN THE POST-GLACIAL HISTORY OF BRITISH VEGETATION 总被引:9,自引:9,他引:0
D. WALKER 《The New phytologist》1955,54(2):222-254
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